Matt Clarke looks at the filter-feeding South American cichlid Chaetobranchopsis orbicularis.
Common name: Filter-feeding cichlid
Scientific name: Chaetobranchopsis orbicularis (Steindachner, 1875)
Origin: Rio Amazonas and Rio Negro in Brazil to the Guapore, Madre and Mamore drainages in Boliva and across to Paraguay.
Size: Around 12-15cm/5-6.
Diet: Despite the enormous mouth, this fish isn t a predator and doesn t have that many teeth. Somewhat unusually it is a filter feeder and is not an easy cichlid to keep. I ve not kept this species, but I have found that the related flavescens would only accept frozen daphnia or brineshrimp. Live Daphnia would be a good choice.
Water: Soft, acidic water is advisable, but neutral or slightly alkaline water should be OK if the fish are carefully acclimated.
Aquarium: Needs a spacious tank. Try keeping a pair or small group in a 120cm/48 tank furnished with bogwood and a sandy substrate. The flavescens I have kept were fairly non-aggressive, so I would imagine that these too should be OK to mix with other fishes without too many problems. Keeping them well-fed is perhaps the biggest hurdle. Some of the food offered is likely to get wasted, so some scavengers and a powerful filter would help keep things in order.
Similar species: This chaetobranchine cichlid is one of a small group of filter-feeding planktivorous species found in the Amazon basin. There are two species in the Chaetobranchopsis genus, orbicularis and C. australis Eigenmann and Ward 1907. The closely related Chaetobranchus genus contains two species, flavescens and semifasciatus. Chaetobranchopsis means Chaetobranchus-like. The quickest way to tell the two genera apart is to count the spinous rays in the anal fin. Chaetobranchopsis have three, while Chaetobranchus have five or six. Chaetobranchopsis australis is bigger than orbicularis (25cm/10) and is found much further south. It has a large black mark on its flank which sits just below the lateral line. C. orbicularis has a slightly diagonal longitudinal stripe, part of which is made up by a darker square in a similar position to the spot of australis.
Availability: These are very rarely kept and I ve only ever seen a handful on sale. We spotted these during the summer at Wholesale Tropicals in London (0207 739 5356).
This article was first published in the January 2006 issue of Practical Fishkeeping magazine.